1. Field of The Invention
This invention relates to a method, apparatus, tool or machine used for slitting insulation covering conductors and wires. After slitting, the insulation may drop off the conductor or may be removed from the conductor by hand or by machine.
2. Description of Related Art
In the manufacture of electrical connectors, it sometimes is desirable to have insulation removed from a wire to expose its conductor prior to connection with a terminal.
Some examples of insulation removal tools for machines are discussed below. U.S. Pat. No. 3,471,916 discloses a tool having knives attached to a mandrel which scrap the insulation and oxides off the conductor as the wire is pulled over the mandrel. U.S. Pat. No. 2,521,688 discloses shearing insulation longitudinally off one edge of each wire, and cutting insulation perpendicular to the wire at the beginning and end of the area to be stripped. U.S. Pat. No. 3,748,932 discloses insulation which first is slit by knives while the wire is moved longitudinally and thereafter cut perpendicularly to the wire with separate cutting blades. These cutting blades not only cut a portion of the insulation but also cause the severed portion of the insulation to buckle away from the conductor to insure that the insulation portion between the perpendicular cuts are removed. U.S. Pat. No. 4,594,921 discloses stripping of insulation from a coaxial cable with heated blades by first making a circumferential cut while the cable is rotating about its longitudinal access and a longitudinal cut with longitudinal movement of the cable.
Although the prior methods of removing insulation have worked well, an attempt has been made to make an insulation slitting apparatus less costly and with fewer moving parts. Also an apparatus was desired which could make slits in the insulation while allowing the slit section to remain in contact with the conductor and easily stripable from the conductor by hand or machine. By allowing the insulation to remain in place until just prior to termination, the conductor is protected from damage caused by the environment. Such damage would include oxides caused by the conductor coming in contact with chemicals or moisture. The presence of oxides on the outer surface of the exposed conductor could result in an incomplete connection or require chemical treatment to remove the oxide barrier. Also, by having the slit section of insulation remain in contact with the conductor until just prior to termination, a stranded type of conductor is prevented from unraveling or untwisting. When untwisting occurs the cross section of the stranded conductor increases which makes it more difficult and sometimes impossible to insert into a crimp type terminal. Finally, scraping the outer surface of the conductor is required in some prior methods of insulation removal. With certain conductors such as the braided type, there is a plated layer on the outer surface. Any scraping will tend to remove this thin outer plated layer.
This invention is directed to solving the above problem by providing a machine with few parts which can slit the insulation of a wire without scraping the conductor surface.